Question

How many oz. of a metal containing 40%

gold must be combined with 7 oz. of a
metal containing 90% gold to form an
alloy containing 75% gold?

Answer 1

3 oz

Explanation:

Let x represent the number of oz. of the medal with 40% gold:

Set up an equation and solve for x:

0.4x + 7(0.9) = 0.75(x + 7)

0.4x + 6.3 = 0.75x + 5.25

6.3 = 0.35x + 5.25

1.05 = 0.35x

3 = x

So, you will need 3 oz. of the metal with 40% gold